Resting Membrane Potential

Question 1

What is a capacitor? What is the cell equivalent?

Answer 1

A capacitor separates and stores charge. The lipid bilayer could be considered a capacitator.

Question 2

What is the charge on the outside vs inside of the cell membrane?

Answer 2

The inside is negative, the outside is positive.

Question 3

Is potassium higher inside or outside the cell?

Answer 3

Inside

Question 4

Is sodium higher inside or outside the cell?

Answer 4

Outside

Question 5

Is calcium higher inside or outside the cell?

Answer 5

Outside

Question 6

Is chloride higher inside or outside the cell?

Answer 6

Outside

Question 7

What is electrical signaling?

Answer 7

short changes in the membrane potential due to current flow through ion channels

Question 8

What determines the direction of current flow?

Answer 8

the net movement of the positive charge

Question 9

Depolarization vs Hyperpolarization

Answer 9

decrease vs increase in charge separation

Question 10

How is uneven ion distribution across the membrane achieved?

Answer 10

Sodium potassium pumps and ion channels

Question 11

What ions are neurons permeable to?

Answer 11

K, Na, Cl

Question 12

What ions are glial cells permeable to?

Answer 12

K

Question 13

What are the two opposing driving forces for where ions travel?

Answer 13

chemical driving force and electrical driving force

Question 14

What is the chemical driving force?

Answer 14

Concentration gradient

Question 15

What is the electrical driving force?

Answer 15

electrical potential difference

Question 16

What is the equilibrium potential?

Answer 16

The difference in electrochemical potential at which there is no net movements of ion X

Question 17

How do you determine equilibrium potential?

Answer 17

Nernst Equation

Question 18

What is the limitation of Nernst Equation?

Answer 18

only applies to single ions that can move through the membrane without changes in permeability

Question 19

What does the presence of Na channels do the membrane?

Answer 19

It slightly depolarizes the membrane

Question 20

T/F: Potassium outward current is balanced by sodium inward current

Answer 20

True

Question 21

T/F: Typical neuronal membrane has a potassium permeability that is 1-10% of the sodium permeability

Answer 21

False: other way around

Question 22

What determines flux of ions?

Answer 22

Electrochemical driving force and the membrane conductance

Question 23

What is the electrochemical driving force?

Answer 23

The difference between membrane potential and equilibrium potential of that ion

Question 24

If electrochemical driving force is positive, do positive ions enter or leave the cell?

Answer 24

They leave the cell

Question 25

What is the Goldman Equation?

Answer 25

Describes the steady state condition of neuronal membranes at rest

Question 26

Who formulated the "membrane hypothesis"?

Answer 26

Julius Bernstein

Question 27

Who worked with giant squid axons?

Answer 27

Hodgkin, Huxley, and Katz

Question 28

How did Hodgkin, Huxley, and Katz find the ratios for ion permeabilities?

Answer 28

They used the Goldman equation

Question 29

Why do we have the simplified Goldman equation?

Answer 29

The Goldman equation does not describe the resting membrane potential fully accurately. it does not factor in the sodium potassium pump

Question 30

What represents conductance in a cell?

Answer 30

leak channel

Question 31

What represents a battery in the cell?

Answer 31

electrochemical gradient

Question 32

T/F: The passive sodium inward current is equal in size to the active sodium outward current, but 1.5x the size of the passive potassium outward current.

Answer 32

True

Question 33

T/F: Chloride has a major contribution to setting the value the resting membrane potential.

Answer 33

False: It has a minor contribution, it stabilizes. K has major contribution.

Question 34

What determines the resting membrane potential?

Answer 34

Equilibrium potential of individual ions and their permeability. (Since K has highest permeability is has largest influence)